Cancer morbidity and mortality is greatly reduced through screening and prevention, but uninsured patients are much less likely than insured patients to receive these evidence-based services as recommended. Similarly, uninsured cancer survivors receive fewer primary and preventive care services than those with health insurance. The Affordable Care Act (ACA) called for every state to significantly expand Medicaid coverage by 2014; it is hypothesized that the ACA's Medicaid expansions could substantially (i) improve access to essential cancer preventive and screening services for previously uninsured patients, and (ii) facilitate better access to routine healthcare among cancer survivors who gain new health insurance. Little is yet known about how ACA Medicaid expansions are impacting the delivery of recommended cancer care. The 2012 United States (US) Supreme Court ruling that made ACA Medicaid expansions optional for states created a natural experiment to answer this important question. As of April 1, 2015, 30 states and the District of Columbia had expanded Medicaid, while 20 states had not. We will use this unprecedented natural experiment to study the effect of state-level Medicaid expansions on rates of cancer screening, cancer preventive services, and healthcare for cancer survivors. We will use electronic health record (EHR) data from the ADVANCE clinical data research network, which has data from 718 community health centers (CHCs), including 476 CHCs in 13 Medicaid expansion states and 242 CHCs in 8 non-expansion states. From this dataset, we will collect detailed information on changes in health insurance and healthcare service receipt, with data spanning 9 years (pre- and post-expansion), comparing states that expanded Medicaid, and those that did not. The specific aims are as follows: Aim 1. Compare pre-post receipt of cancer prevention and screening among CHC patients in Medicaid expansion versus non-expansion states. Aim 2. Compare pre-post insurance status, visits, and receipt of routine, recommended primary and preventive care among cancer survivors seen in CHCs in expansion versus non-expansion states. Aim 3. Compare pre-post cancer prevention, screening, and survivor care for newly insured (gained Medicaid in post-period), already insured (had Medicaid coverage in pre- and post-periods), and continuously uninsured (no coverage in pre- and post-periods) CHC patients in states that expanded Medicaid. This project builds on our team's experience studying health insurance, primary care, and receipt of preventive services. The ADVANCE dataset positions us uniquely to study national-level impacts of the ACA. Importantly, this project aligns with National Cancer Institute (NCI) goals to increase knowledge regarding cancer control and prevention. According to the NCI, prevention has the potential to save more lives from cancer than treatment...which underlines the importance of strongly supporting this research area. Also, findings will be relevant to policy and practice, and will inform further improvements in the US healthcare system to mitigate disparities in cancer prevention and survivor care for vulnerable populations.